I've been wanting to do this forever, but this Pen http://codepen.io/Tresva/pen/dxHsb finally pushed me over the edge to do it.
Hacker news if anyone feels like it: https://news.ycombinator.com/item?id=6493590

Quick googling turned up some people who had the idea a while back [1](http://www.jonathoncihlar.com/index.php?Post=nutritiontemplate) [2](http://aggregated.alanhogan.com/post/1565663374/i-would-love-to-see-something-like-this-alongside)